Consumers use paper-wiping products, such as facial tissues and bath tissues, for a wide variety of applications. Facial tissues are not only used for nose care but, in addition to other uses, may also be used as a general wiping product. Consequently, there are many different types of tissue products currently commercially available.
In some applications, tissue products are treated with polysiloxane lotions in order to increase the softness of the tissue. Adding silicone compositions to a tissue may impart improved softness to the tissue while maintaining the tissue's strength and while reducing the amount of lint produced by the tissue during use.
In some applications, tissue products may be treated with other beneficial agents as well. For example, in addition to softening agents such as polysiloxane lotions, other desirable agents may be added to a tissue in order to provide a benefit to the user. For example, vitamins, plant extracts, medications, antimicrobial compounds, and the like may also be added to the web in order to transfer the desired agent to the consumer upon use.
In the papermaking industry, various manufacturing techniques have been specifically designed to produce paper products which consumers find appealing. Manufacturers have employed various methods to apply chemical additives, such as silicone compositions and other beneficial agents, to the surface of a tissue web. Currently, one method of applying chemicals to the surface of a tissue web is the rotogravure printing process. A rotogravure printing process utilizes printing rollers to transfer chemicals onto a substrate. Chemicals that are applied to webs using the rotogravure printing process typically require the addition of water, surfactants, and/or solvents in order to prepare an emulsion to be printed onto the substrate. Such additions are not only costly but also increase wet-out time, drying time, and add process complexity.
Another method of applying chemical additives to the surface of a tissue web is spray atomization. Spray atomization is the process of combining a chemical with a pressurized gas to form small droplets that are directed onto a substrate, such as paper. One problem posed with atomization processes is that manufacturers often find it difficult to control the amount of chemical that is applied to a paper ply. Thus, a frequent problem with spray atomization techniques is that a large amount of over-spray is generated, which undesirably builds upon machinery as well as the surfaces of equipment and products in the vicinity of the spray atomizer. Furthermore, over-spray wastes the chemical being applied, and comprises a generally inefficient method of applying additives to a tissue web. Additionally, lack of control over the spray atomization technique also affects the uniformity of application to the tissue web.
In view of the above, a need exists in the industry for improving the method for application of chemical additives to the surface of a paper web.
Further, besides the above-mentioned difficulties in applying chemical additives to the surface of a paper web, some additives, such as softening agents, may also have a tendency to impart hydrophobicity to the treated paper web. Although hydrophobicity may be desirable in some applications, in other applications, increased hydrophobicity may adversely affect the product. For instance, increased hydrophobicity in a bath tissue may prevent the bath tissue from being wetted in a sufficient amount of time and prevent disintegration and dispersing when disposed in a commode or toilet. Hence, in some applications, it is difficult to find a proper balance between softness and absorbency, both of which are desirable attributes for tissues, particularly bath tissues.
Thus, a need also exists for a process of applying hydrophobic compositions to tissues for providing benefits to the tissue without increasing the hydrophibicity of the tissue beyond desirable limits.